1. Field of the Invention
The present invention relates to an electrically driven hand-held power tool with an angle drive such as angular grinder, drilling, chiseling, or screw-driving tool, or, in particular, a circular saw.
2. Description of the Prior Art
An angle drive of hand-held power tools of the type described above includes a drive toothing provided on a drive shaft driven by a motor in a preferable drive direction about a drive axis, and a driven toothing provided on a driven shaft which is driven in a preferable driven direction about a driven axis and is connected with a tool holder for the working tool. The driven toothing cooperates with the drive toothing for driving the driven shaft in the preferable drive direction in response to the drive shaft being driven in the preferable drive direction.
The advantage of hand-held tools with angular drives consists in that the drive axis can be arranged at an angle, in particular, a right angle to the driven axis. This makes possible a particularly compact design of the hand-held power tools.
German Publication DE 295 01 974 discloses an electrical hand-held power tool with an angle drive and in which the drive shaft is supported by a roller bearing that is supported at its side remote from the driven shaft in an axial direction against a support wall. The toothings of the angle drive are so formed that the drive shaft, upon application of an increased resistive torque to the driven shaft, as it is common during the start of the operation of a hand-held power tool, is accelerated in a direction away from the driven shaft and can be supported, via the roller bearing, against the support wall. Thereby, an axial displacement backlash of the drive toothing relative to the driven toothing can be reduced.
The limitation of the displacement backlash permits to eliminate a zero backlash between the toothings of the angle drive and the resulting increased wear or possible damage.
The drawback of the power tool of DE 295 01 974 consists in that the axial support is provided with the roller bearing. This is, in particular, because with high-power hand-held power tools, particularly high torque peaks are generated and, therefore, particularly expensive roller bearings are necessary in order to ensure a satisfactory limitation of the axial backlash. This results in high manufacturing costs and increase in weight. There is also the danger of increased hammering of the roller bearing with time which would lead to increased axial displacement backlash with time. This could lead to increased wear or damage of the angle drive.
Accordingly, an object of the present invention is to provide a hand-held power tool in which the drawbacks of the known prior art hand-held power tool are eliminated.
Another object of the present invention is to provide a hand-held power tool which would ensure a lasting limitation of the axial displacement backlash of the drive toothing relative to the driven toothing.